/*
    变量演示
*/
#include <stdio.h>
int num;
int main() {
    printf("num是%d\n",num);
    int num = 1;
    printf("num是%d\n",num);
    {
        printf("num是%d\n",num);
	int num = 2;
        printf("num是%d\n",num);
    }
    printf("num是%d\n",num);
    return 0;
}
